In general, a building, for example, a house is mainly formed of pillars, a wall, and a roof, and the pillars stand on the ground by means of a concrete foundation. With a building in which pillars are incorporated, the Building Standards Act in Japan specifies thickness of a pillar and the number of stories, and the like in accordance with the number of story of the building. In addition, as the number of story is increased, an occupancy ratio of the pillars in the building is increased and as a result, utilization efficiency is decreased. Further, since a periphery of the building built on the ground is exposed to the outside air, enormous energies are uselessly discharged from the building, so that global warming is increased.
Therefore, the present applicant (also the inventor of the present application) has invented an underground structure with which a group of pillars standing from the ground can be eliminated and cooling and heating effects are improved, and filed a patent application seeking a patent on the invention which was disclosed in Japanese Patent Application JPA-H06-346476. This underground structure includes a peripheral wall section defining therein a space of mortar-shape in the underground, a plurality of supporting members provided around the mortar-shape space to have respective heights reaching the same plane, beams, each having ends supported by the plurality of supporting means, a story structural body having floor sections arranged in a central part thereof at least with a predetermined spacing from the peripheral wall section, and stairs provided in an up and down direction so that the upper end thereof reaches the aboveground along the peripheral wall section and the lower part thereof arrives at the floor sections of the story structural body. Thus, the story structural body is supported by the plurality of supporting members so that each of the floors may be independent. Entrance and exit of the floors are made easier, safety can be improved, energies can be saved, and construction cost can be reduced.
The inventor of the present applicant has invented an underground structure in which a covering member is detachably provided in an upper space part of an uppermost floor section of a story structural body in a similar structure to the Japanese Patent Application JPA-H06-346476 described above, and filed a patent application seeking a patent for that invention which was disclosed in Japanese Patent Application JPA-H06-346478. According to this latter structure, an underground space having a mortar-shape can be blocked and isolated from the outside air, so that the underground space can be used as, for example, a nuclear shelter.